Overview
ISO/TS 5660-4:2016 - Reaction-to-fire tests - Part 4: Measurement of low levels of heat release - specifies a cone-calorimeter based method for evaluating materials and products that produce low levels of heat release when exposed to high irradiance typical of fully developed fires. The technical specification is targeted at specimens that yield a total heat release of about 0.75 MJ/m² to 15 MJ/m² and complements ISO 5660‑1 by prescribing specimen size, holder, orientation, volumetric flow for O2 analysis and the irradiance conditions for testing.
This method uses the oxygen-consumption principle (heat release calculated from measured O2 depletion) and provides standardized procedures for apparatus, calibration, test environment, data collection and reporting.
Key Topics and Requirements
- Scope and suitability: Intended for products with only small amounts of combustible elements; not suitable for materials with moderate-to-high heat release (those are covered by ISO 5660‑1).
- Apparatus and setup: Cone-shaped radiant electrical heater, radiation shield, specimen holder and retainer frame, weighing device, exhaust duct and flow metering, gas sampling and oxygen analyser, heat flux meters, calibration burner, and data acquisition system.
- Specimen preparation: Defined specimen construction, conditioning and wrapping rules to ensure repeatable low-level heat-release measurements.
- Test conditions: Prescribed irradiance levels, specimen orientation and volumetric flow rates for O2 analysis to reliably capture low heat-release behavior under high radiant flux.
- Calibration and accuracy: Procedures for initial and operating calibrations (weighing response, oxygen analyser delay/noise/drift, heat flux meter calibration and calibration burner checks) and guidance on measurement linearity and limits.
- Data and calculations: Calculation methods for heat release rate by oxygen consumption, mass loss rate, exhaust mass flow, and reporting of test limitations.
- Safety: Warnings about high temperatures, combustion products and the need to pre-screen specimens (e.g., small 100 × 100 mm test per ISO 5660‑1) to avoid hazardous conditions.
Applications and Users
ISO/TS 5660-4:2016 is used by:
- Fire test laboratories for standardized measurement of low heat-release materials.
- Manufacturers and product developers assessing low-combustibility finishes, insulation, coatings, and composites.
- Fire safety engineers and consultants for fire performance data to inform risk assessments and engineering designs.
- Regulators and certification bodies for conformity assessment, product classification and regulatory compliance.
- Research institutions studying combustion behavior and material flame retardance at low heat-release regimes.
Keywords: ISO/TS 5660-4:2016, reaction-to-fire tests, heat release, cone calorimeter, low levels of heat release, oxygen consumption, smoke production, mass loss rate, irradiance.
Related Standards
- ISO 5660-1:2015 - Heat release rate (cone calorimeter method)
- ISO 5660-3 - Guidance on measurement
- ISO 291 and ISO 554 - Conditioning and standard atmospheres for testing